At the time period in question, Graflex made two kinds of camera. One kind, in various models, was a big reflex type with a swinging mirror inside. The other, a "press" camera, did not have the mirror. Both had a simple but effective focal-plane shutter.

The reflexes made a noise that might be rendered "clunk"-(when the mirror went up)-"zzipt!" (as the focal plane shutter traveled). The press types simply went "zzipt!"